The present disclosure relates generally to fluid storage, and specifically to boss for a fluid containment container and a method for mounting the fluid containment container using the boss. A particularly suitable fluid containment container is a pressure vessel. A typical pressure vessel includes a load bearing outer shell and a fluid impermeable inner liner.
Suitable pressure vessel shell materials include metals, such as steel; or composites, which may include laminated layers of wound fiberglass filaments or other synthetic filaments bonded together by a thermal-setting or thermoplastic resin. The fiber may be fiberglass, aramid, carbon, graphite, or any other generally known fibrous reinforcing material. The resin material used may be epoxy, polyester, vinyl ester, thermoplastic, or any other suitable resinous material capable of providing fiber-to-fiber bonding, fiber layer-to-layer bonding, and the fragmentation resistance required for the particular application in which the vessel is to be used. Details relevant to the formation of an exemplary pressure vessel are disclosed in U.S. Pat. No. 4,838,971, entitled “Filament Winding Process and Apparatus,” which is incorporated herein by reference.
An elastomeric or other non-metal resilient liner or bladder often is disposed within the composite shell to seal the vessel and prevent internal fluids from contacting the composite material. The liner can be manufactured by compression molding, blow molding, injection molding, or any other generally known technique. Alternatively, the liner can be made of other materials, including steel, aluminum, nickel, titanium, platinum, gold, silver, stainless steel, and any alloys thereof. Such materials can be generally characterized as having a high modulus of elasticity. In one embodiment, the liner is formed of blow molded high density polyethylene (HDPE).
The composite construction of the vessels provides numerous advantages such as lightness in weight and resistance to corrosion, fatigue and catastrophic failure. These attributes are due at least in part to the high specific strengths of the reinforcing fibers or filaments. Such composite vessels are commonly used for containing a variety of fluids under pressure, such as hydrogen, oxygen, natural gas, nitrogen, methane, propane, and rocket or other fuel, for example. Generally, pressure vessels can be of any size or configuration. The vessels can be heavy or light, single-use (i.e., disposable), reusable, subjected to high pressures (greater than 50 psi, for example), low pressures (less than 50 psi, for example), or used for storing fluids at elevated or cryogenic temperatures, for example. Descriptions relevant to pressure vessels are presented in U.S. Pat. No. 5,476,189, entitled “Pressure vessel with damage mitigating system,” which is hereby incorporated by reference.
Composite pressure vessels of the character described above originally were developed for aircraft and aerospace applications primarily because of the critical weight restrictions in such vehicles. As compressed natural gas (CNG) has become more widely used in ground-based vehicles such as buses and cars, however, the composite pressure vessel has become more widely used. The structural requirements of a pressure vessel are such that a generally cylindrical shape having rounded ends is a highly-desirable form factor from a standpoint of both strength and packing efficiency. However, the rounded shape can make securing such a pressure vessel to a vehicle difficult.
The neck of the compressed gas cylinder provides a structural protrusion suitable for attachment by a collar or similar device. Certain known designs make use of this feature to secure a gas cylinder. However, such designs suffer from a number of drawbacks. Some designs handle misalignment poorly and can place substantial stresses on the neck structure in the event of misalignment. Other designs inadequately secure the neck, so that there is a risk that the cylinder may detach from the mount under certain conditions. Moreover, in some cases, the cylinder can rotate about the principal axis of the cylinder, thereby placing stress on connection lines or other attached hardware.